The present invention relates to a method, system and device for optimizing the suspension of a vehicle, and, in particular for optimizing the suspension of a race car.
In the automobile design industry and in automobile racing, optimizing the suspension of a vehicle is critical to the vehicle's performance. The current practice includes, running the vehicle or race car through a plurality of test cycles using different suspension setups which have to be manually adjusted, and then taking the results of those tests to determine the optimal suspension design. The test cycles could include many different types of tests, including, laps around a test track or a seven post test.
The seven post test is conducted on a seven post shaker, which is also referred to as a seven poster or a shaker rig. The seven post shaker is an expensive piece of test equipment used to perform vehicle dynamics analysis for any vehicles, but is mainly used for racecars. The seven post shaker is comprised of four hydraulic rams, one underneath each wheel and three connected to the chassis. A seven post shaker can apply all vertical forces seen by the car on any road or surface, like a racetrack. This simulates the conditions of driving the car on the road or racetrack without actually driving it on the road or racetrack. Included with the shaker rig are an exceptional amount of controls for the hydraulic system and also many sensors to detect what is happening to the car as it is exposed to the virtual road and the associated forces. These forces include banking loads, lateral load transfer, acceleration, braking and aerodynamic downforce. The seven poster doesn't apply longitudinal or lateral acceleration forces. i.e. there are no rams in either direction. Thus you can simulate the pitch and roll motions including the weight transfer between the wheels but not the reaction forces at the tires and suspension associated with the directions of acceleration, braking or cornering. This analysis allows the chassis engineer to replicate the actual corner loads seen on the road or at the track, and to analyze the interaction between suspension setups and the resulting corner loads. This detailed analysis is especially required at high levels of racing.
The current seven post test is used by a multitude of vehicles for different driving conditions, like racing. There are also earlier versions of the seven post shaker, such as the five post shaker and a four post shaker. The four post shaker is commonly used by vehicle manufacturers to determine if their vehicles will handle specific road inputs. For example, the seven post test is highly used by most NASCAR® teams. Aside from NASCAR®, other racing entities that highly use this advanced technology include Champ Car and the Indy Racing League.
The seven post test is an engineering system unto itself as it places dynamic and quasi-static forces on a vehicle and records the reaction forces that the vehicle puts back into the system. The forces that the seven shaker applies to the vehicle are lift, downforce, pitch, roll, heave, and road surface irregularities. The vehicle's suspension and drivetrain components feel these forces in the form of dynamic input that result in chassis and suspension frequency oscillations (under 30 Hz), and tire, engine, transmission and drive axle vibrations up to 500 Hz. These input forces can be derived from a model of the racetrack, or actual test data recorded from the vehicle as it travels the race track.
When testing on the seven post shaker, all variables are inter-related and can be analyzed while the effects of the actual suspension, tires, etc. installed can be quantified. For example, damping force curve of the suspension can be extracted from the data to understand how installation stiffness and other variables affect the damping force. Vehicle designers can use the results of the testing on the seven post shaker to adjust specific aspects of the vehicle. They can adjust spring rates, shock valving, and many other factors.
Although, the use of electronically adjustable shocks, i.e., active suspensions, is known, a system is needed to try to emulate a passive shock in order to speed up suspension development for those vehicles that can not use active suspensions. Current systems are only designed to use sophisticated control algorithms to improve dynamics via active shocks. However, no shock systems have been used in the development of passive vehicle suspensions. For example, in NASCAR®, and many racing leagues, passive shocks are required by rule. As a result, emulating the actual passive suspensions used on the racecar while testing is crucial to acquiring the most accurate information for optimizing the vehicle's suspension. Another common example of the need for this type of system would be for automobile designs that are designed with passive shock suspensions. Thus, there is clearly a need for a passive shock system that can be used in testing that correlates with the actual shocks used in racing.
One problem with the seven post test is the cost and time associated with testing the vehicle. The cost of testing a vehicle on a seven post machine is very expensive and is typically calculated on a per hour basis. A good portion of the time associated with seven post tests is spent manually adjusting the damping forces of the shocks, or changing out the shocks completely, between each test cycle. The shocks have to be adjusted or changed according to the data collected in order to try to optimize the vehicles suspension by providing different damping forces of each shock. This time is a significant factor in the total price of running a vehicle on a seven post test. Furthermore, most teams have only one seven post rig used to test multiple cars which all need to be tested on the rig before each race, which only compounds the time required for manually adjusting or changing out shocks. Thus time becomes more limited as the seven post is used more extensively for race car development Thus, there is a need to reduce or eliminate the time spent manually adjusting the damping forces of each shock, or manually changing out one or more shocks.
In addition to the time and cost factor associated with manually adjusting and changing the shocks between test cycles, there is also a great risk of human error in manually adjusting or changing the shocks. Any slight human error can greatly reduce the accuracy of the seven post test. Thus, there is a need to improve the accuracy of the testing by reducing or eliminating the risk of human error associated with adjusting or changing the shocks in between test cycles.
Furthermore, the data collected at a standard seven post testing facility is limited to what data the testing facility is capable of collecting. However, the more data collected, the more highly optimized the vehicle's suspension can be equipped, especially, in the racing industry. Thus, there is a need to increase the amount of data collected during testing for further optimizing the vehicle's suspension.
The instant invention is designed to address the above mentioned problems.